Ivermectin has been shown in trials in both South India and elsewhere to be very effective in clearing microfilaremia in patients with bancroftian filariasis. Current studies in South India and Brazil (coordinated with trail elsewhere in the world) are focussed on developing a regimen to optimize the duration of microfilarial clearance. Recent investigation has indicated that the Tropical Pulmonary Eosinophilia syndrome can be caused by strongyloides as well as by filariae. Work to differentiate these two pulmonary eosinophilic conditions and develop appropriate therapy is underway. Loiasis in expatriate visitors to endemic areas has been characterized as having marked clinical and immunologic hyperresponsiveness to the filarial parasite. The hypothesized state of hyporesponsiveness, both clinical and immunological, in infected individuals native to the endemic regions has now been demonstrated by studies in Benin, West Africa. A therapeutic trial of albendazole for loiasis is also underway there.